The invention relates to a tire pressure control system for a motor vehicle, comprising a rotary feedthrough having a stator and a rotor for transferring compressed air, fed from a compressed air source on the vehicle side to the rotor designed for supporting a wheel, rotary feedthrough which comprises an annular chamber present between the rotor and the stator that can be sealed off by activatable seals, into which both a stator side and a rotor side channel open. The invention further relates to a feedthrough for a tire pressure control system.
Tire pressure control systems are used in motor vehicles, particularly in commercial vehicles such as trucks, tractors or earth moving machines, to allow the tire pressure in the tire to be adapted different operating situations of the motor vehicle. A desired adaptation of the tire pressure depends on the ground to be driven on and/or of the load. The footprint of the tire can be modified depending on the tire pressure. A tire has a larger footprint with a lower tire pressure than with a higher tire pressure. For this reason, it is preferable to drive with a lower tire pressure and with a larger footprint if the ground is soft than in the case of a consolidated road surface. The tire pressure can also be changed as a function of the given loading state.
Such tire pressure control systems comprise a rotary feedthrough to transfer compressed air from a vehicle side source to the rotatably mounted wheel to increase the inner tire pressure. The rotary feedthrough has a stator on the vehicle side and a rotor on the wheel side which separated from said stator by a movement gap. The stator and the rotor are arranged axially with respect to each other and with respect to the rotary axis of the wheel. The stator and the rotor have annular mutually opposite the movement slit for the transfer of compressed air, and mutually facing open grooves or chambers which are sealed off by activatable seals, as described in EP 1 095 799 B1, during the compressed air transfer in order to form a compressed air transfer chamber. On the wheel side, an air duct leading to the rim of the wheel is arranged on the rotor. Said air duct passes through an opening in the rim, and it opens into the tire interior. Typically, a controllable valve is inserted in the wheel side air duct. The valve is opened to regulate the tire pressure, and closed after the completion of the process. The pressurized air itself is provided by a compressor arranged on the vehicle side. Typically, the compressor that is present in any case in commercial vehicles for operating the braking system is used.
Increasingly, tire pressure control systems are also used in passenger cars. When such tire pressure control systems are used in passenger cars, problems arise due to the fact that, in contrast to commercial vehicles, there is very little installation space on or near the hub for a rotary feedthrough. In passenger cars tire pressure control installations are used primarily to provide an optimal tire pressure in each case, as a function of the loading, to achieve as optimal as possible a rolling motion of the wheel in terms of resistance to rolling to reduce the fuel consumption.
Although the tire pressure control system disclosed in EP 1 095 799 B1 can be used without problem in commercial vehicles, it is not sufficiently compact in its structure to be used in a passenger car. Moreover, due to rotors turning at higher rotation speeds in comparison to commercial motor vehicles, the seals applied against them undergo wear more rapidly. Due to the friction-caused heating in the case of activated seals, it can sometimes be necessary to apply an appropriately high pressure for the purpose of sealing off the compressed air transfer chamber.
On the basis of the discussed prior art, the invention therefore is based on the problem of improving a tire pressure control system of the type mentioned at the start, in such a manner that it can be installed even under the tight installation conditions of a passenger car and that it also meets the requirements placed on such a rotary feedthrough in a passenger car caused by the higher rotation speeds.
The foregoing example of the related art and limitations related therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the drawings.